Two-dimensional (2D) carbon materials, such as graphene, have attracted particular attention owing to the exceptional carrier transport characteristics that arise from the unique π-electron system in their conjugated carbon network structure^1,2,3,4. To complement zero-bandgap graphene, material scientists have devoted considerable effort to identifying 2D carbon materials^5,6,7,8. However, it is a challenge to prepare large-sized single-crystal 2D carbon materials with moderate bandgaps^5,9. Here we prepare a single-crystal 2D carbon material, namely monolayer quasi-hexagonal-phase fullerene (C₆₀), with a large size via an interlayer bonding cleavage strategy. In this monolayer polymeric C₆₀, cluster cages of C₆₀ are covalently bonded with each other in a plane, forming a regular topology that is distinct from that in conventional 2D materials. Monolayer polymeric C₆₀ exhibits high crystallinity and good thermodynamic stability, and the electronic band structure measurement reveals a transport bandgap of about 1.6 electronvolts. Furthermore, an asymmetric lattice structure endows monolayer polymeric C₆₀ with notable in-plane anisotropic properties, including anisotropic phonon modes and conductivity. This 2D carbon material with a moderate bandgap and unique topological structure offers an interesting platform for potential application in 2D electronic devices.

二维 (2D) 碳材料，如石墨烯，由于其共轭碳网络结构^1,2,3,4中独特的 π 电子系统产生的特殊载流子传输特性而引起了特别的关注。为了补充零带隙石墨烯，材料科学家投入了大量精力来识别二维碳材料^5,6,7,8。^{然而，制备具有中等带隙5,9}的大尺寸单晶二维碳材料是一项挑战。在这里，我们通过层间键合裂解策略制备了具有大尺寸的单晶二维碳材料，即单层准六方相富勒烯（C _{60 ）。}在这种单层聚合物 C ₆₀，C ₆₀的簇笼在一个平面内相互共价键合，形成与传统二维材料不同的规则拓扑结构。单层聚合物C ₆₀具有高结晶度和良好的热力学稳定性，电子能带结构测量显示传输带隙约为1.6 电子伏特。此外，不对称晶格结构赋予单层聚合物C ₆₀显着的面内各向异性特性，包括各向异性声子模式和电导率。这种具有中等带隙和独特拓扑结构的二维碳材料为二维电子器件的潜在应用提供了一个有趣的平台。